• Korean Journal of Food Science and Technology
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• v.51 no.4
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• pp.404-409
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• 2019

This study was performed to determine the optimum conditions for the production of gaseous chlorine dioxide ($ClO_2$) from aqueous $ClO_2$ (HCl+$NaClO_2$). When 1 N HCl was reacted with various concentrations of $NaClO_2$ (50,000-500,000 mg/mL), the highest concentration (695 mg/L) of gaseous $ClO_2$ was obtained from the aqueous $ClO_2$ containing $100,000{\mu}g/mL$ $NaClO_2$. Next, the effects of relative humidity (RH; 43, 85, and 100%) and temperature (4, 12, and $25^{\circ}C$) on the production of gaseous $ClO_2$ were investigated. It was observed that the concentration of gaseous $ClO_2$ was increased as RH was decreased, or the temperature was increased. Finally, it was confirmed that the amount of gaseous $ClO_2$ was highly correlated ($R^2=0.9546-0.9992$) with the volume of aqueous $ClO_2$. The results of this study provide useful information for designing a sanitization program using gaseous $ClO_2$ under various environmental conditions.

• Food Science and Preservation
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• v.15 no.5
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• pp.754-759
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• 2008

The effect of citric acid-aqueous chlorine dioxide ($ClO_2$) treatment of radish seeds artificially contaminated with Salmonella typhimurium was studied. Radish seeds were inoculated by immersion, in more than 106 log CFU/g seed, of a suspension of S. typhimurium, dried, and stored sealed at $4^{\circ}C$ Radish seeds soaked in 200 ppm aqueous ClO2 solution for 10 min showed a bacterial reduction of 1.08 log CFU/g seed, and the lowering of microbial burden noted in seeds soaked in 2% (w/v) citric acid solution for 10 min was 2.89 log CFU/g seed. Next, radish seeds were exposed to 0.5% (v/v) glycerol solution for 10 min either before or after treatment with 200 ppm aqueous ClO2 or 2% (w/v) citric acid for 10 min. Glycerol exposure after citric acid treatment reduced bacteria by 3.46 log CFU/g seed, and glycerol treatment after aqueous $ClO_2$ treatment reduced the microbial burden by 2.14 log CFU/g seed. Both glycerol treatments yielded better elimination of S. typhimurium than did a single treatment with either citric acid or aqueous $ClO_2$. Radish seeds inoculated with S. typhimurium were treated throughout the entire growth period. Although radish seed treatment was effective, treatment by citric acid and aqueous $ClO_2$ after sprouting was not effective to eliminate S. typhimurium.

• Food Science and Preservation
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• v.16 no.6
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• pp.1013-1017
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• 2009

The effects of aqueous chlorine dioxide ($ClO_2$) or fumaric acid treatment on the reduction of microbial populations in hot pepper, ginger, and carrot, were investigated. Hot pepper, ginger, and carrot were treated with 5, 10, or 50 ppm of $ClO_2$, or 0.1, 0.3, or 0.5%(v/v) fumaric acid solution for 5 min. Aqueous $ClO_2$ or fumaric acid treatment significantly decreased the populations of both total aerobic bacteria, and yeasts and molds. In particular, 50 ppm $ClO_2$ treatment of hot pepper reduced total aerobic bacteria and yeast and mold levels, by 1.52 and 1.81 log CFU/g, respectively, whereas 0.5% (v/v) fumaric acid treatment eliminated all aerobic bacteria and all yeasts and molds. In addition, 50 ppm $ClO_2$ treatment of ginger reduced the populations of total aerobic bacteria, and yeasts and molds, by 0.53 and 0.92 log CFU/g, respectively, and 0.5% (v/v) fumaric acid treatment also decreased total aerobic bacteria, and yeast and mold levels, by 1.44 and 1.28 log CFU/g, respectively. With carrots, 50 ppm $ClO_2$ treatment decreased total aerobic bacteria, and yeasts and molds, by 1.76 and 2.22 log CFU/g, whereas 0.5% (v/v) fumaric acid treatment reduced the levels of these microorganisms by 1.94 and 1.73 log CFU/g, respectively. These results indicate that aqueous $ClO_2$ or fumaric acid treatment is useful for reducing microbial populations in hot peppers, ginger, and carrots.

• The Korean Journal of Food And Nutrition
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• v.28 no.3
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• pp.396-403
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• 2015

To improve the shelf-life of cherry tomato, samples were treated with aqueous chlorine dioxide ($ClO_2$) at 30 ppm for 0~30 minutes and the weight loss rate as well as the changes in physico-chemical and sensory properties of treated samples were investigated. Weight change in the control and in the samples with aqueous $ClO_2$ treatment were decreased slightly, and there were no difference during the storage period. There were no differences in soluble solid content among the treatments and during the storage period. There were no differences in the firmness of samples among the treatments but the firmness of the aqueous $ClO_2$ treated samples were decreased slower than that of the control samples. No significant changes in lightness, redness and yellowness of the controls and the samples by aqueous $ClO_2$ treatment were observed during 4 weeks storage period. The sensory parameters including taste, flavor, color, texture and overall acceptance at the initial period did not differ among the treatments. The scores for taste, texture and overall acceptance of the control were decreased faster than those of the aqueous $ClO_2$ treated samples when 3 weeks reached.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.3
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• pp.402-407
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• 2012

The effects of a combined treatment of aqueous chlorine dioxide ($ClO_2$) and ultraviolet-C (UV-C) irradiation on microbial growth in celery and cherries were investigated. Celery and cherry samples were treated with 50 ppm $ClO_2$, UV-C at dose of 10 kJ/$m^2$, and a combination of $ClO_2$ and UV-C. The changes in the counts of Escherichia coli O157:H7 inoculated in the celery and cherries as well as those of total aerobic bacteria, yeast and molds in the celery and cherries were investigated after each treatment. After the combined treatment of aqueous $ClO_2$ and UV-C irradiation, the populations of E. coli O157:H7 in the inoculated celery and cherries were reduced by 2.8 and 3.0 log CFU/g, respectively, compared to those of the control. For the un-inoculated celery and cherries, the populations of total aerobic bacteria were reduced by 2.9 and 1.8 log CFU/g, respectively, compared to the control. In addition, the populations of yeast and molds were decreased by 1.8 and 1.2 log CFU/g, respectively. These results suggest that the combined treatment of 50 ppm $ClO_2$ and UV-C at a dose of 10 kJ/$m^2$ would be an effective technology for decontamination and improving the microbiological safety in celery and cherries during chilled storage.

• Food Quality and Culture
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• v.3 no.1
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• pp.34-39
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• 2009

This study assessed the efficacy of aqueous chlorine dioxide ($ClO_2$) and commercial chlorine sanitizer in terms of its ability to eliminate Listeria monocytogenes, Salmonella Typhimurium, and Escherichia coli O157:H7 on radish sprouts (Raphanus sativus L.). Radish sprouts were inoculated with a cocktail containing one each of three strains of three different foodborne pathogens, then treated with distilled water (control) or chemical sanitizers (100 ppm commercial chlorine, and 50, 100, 200 ppm $C1O_2$) for 1, 5, and 10 min at room temperature ($22{\pm}2^{\circ}C$). Populations of S. Typhimurium, E. coli O157:H7 and L. monocytogenes were counted at 4.64, 6.05, and 4.29 log CFU/g, respectively, after inoculation. Treatment with water did not significantly reduce the levels of any of the three foodborne pathogens. The levels of all three pathogens were reduced by treatment with chemical sanitizers; however, the observed levels of reduction of E. coli O157:H7 and L. monocytogenes were not significant as compared with the controls. The levels of the three pathogens were reduced most profoundly when treated for 10 min with 200 ppm of $C1O_2$, and the reduction levels of S. Typhimurium, E. coli O157:H7, and L. monocytogenes were 1.17, 1.63, and 0.96 log CFU/g, respectively. When chemically injured cells were investigated using SPRAB for E. coli O157 :H7 and by selective overlay methods for S. Typhimurium and L. monocytogenes, respectively, it was noted that commercial chlorine sanitizer generated more numbers of injured pathogens than did $C1O_2$. These data indicate that $C1O_2$ treatment may prove useful in reducing the numbers of pathogenic bacteria in radish sprouts.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2004.11a
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• pp.449-450
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• 2004

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.275-282
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• 2010

A characteristic study of aqueous chlorine dioxide generation from sodium chlorite($NaClO_2$) by an undivided electrochemical cell with different anode materials were performed. $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA were used as anode materials and Pt-coated Ti electrode was used as cathode. Various electrochemical cell operating parameters such as cell residence time($t_R$), initial feed solution pH, sodium chlorite and sodium chloride(NaCl) concentration and applied current for the generation of chlorine dioxide in an un-divided cell were investigated and optimized. Estimated optimal cell residence times in $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode material systems were around 2.27, 1.52 and 1.52 sec, respectively. Observed optimum initial feed solution pH was around 2.3 in all anode material systems. Optimum sodium chlorite concentrations in $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode systems were around 0.43, 0.43 and 0.32 g/L, respectively. Optimum electrolyte concentration and applied current were around 5.85 g/L and 0.6 A in all anode systems. Current efficiencies of $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode systems under optimum conditions were 79.80, 114.70 and 70.99%, respectively. Obtained energy consumptions for the optimum generation of chlorine dioxide were 1.38, 1.03 and $1.61W{\cdot}hr/g-ClO_2$, respectively.

• Journal of Microbiology and Biotechnology
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• v.27 no.2
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• pp.219-225
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• 2017

An aqueous chlorine dioxide ($ClO_2$) treatment combined with highly activated calcium oxide (CaO) and mild heat was tested for inactivating naturally existing bacteria and Escherichia coli O157:H7 inoculated on fresh-cut kale. Kale samples were treated with different concentrations of $ClO_2$ (10, 30, and 50 ppm), CaO (0.01%, 0.05%, 0.1%, and 0.2%), and mild heat ($25^{\circ}C$, $45^{\circ}C$, $55^{\circ}C$, and $65^{\circ}C$) as well with combinations of 30 or 50 ppm $ClO_2$ and 0.2% CaO at $55^{\circ}C$ for 3 min. An increasing concentration of $ClO_2$ and CaO significantly reduced the microbial population compared with the control. In addition, mild heating at $55^{\circ}C$ elicited greater microbial reduction than the other temperatures. A combined treatment of 50 ppm $ClO_2$ and 0.2% CaO at $55^{\circ}C$ reduced the population of naturally existing bacteria on kale by 3.10 log colony forming units (CFU)/g, and the counts of E. coli O157:H7 were below the detection limit (1 log CFU/g). In addition, no significant differences in the Hunter color values were evident in any treatment during storage. Therefore, a combined treatment of $ClO_2$ and active CaO at $55^{\circ}C$ can be an effective sanitizing method to improve the microbiological safety of fresh-cut kale without affecting its quality.

• The Korean Journal of Food And Nutrition
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• v.27 no.5
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• pp.881-887
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• 2014

To prolong the shelf-life of domestic peaches, samples were treated with 30 ppm of aqueous chlorine dioxide ($ClO_2$) for 0~15 minute, after which the spoilage rate, changes in physico-chemical and sensory properties of treated samples were investigated. The control showed spoilage at day 4, and then 31.25% of control showed spoilage at day 8. However, samples treated with aqueous $ClO_2$ had no spoilage at day 4. On day 6, only 6.25% of samples treated with aqueous $ClO_2$ for 5 min showed spoilage. After 8 days, no spoilage was observed for samples treated with aqueous $ClO_2$ for 10 and 15 min. The weight change of the control was higher than that of aqueous $ClO_2$ treated samples for 8 days of storage. There were no differences in pH of samples among the treatments, but they were increased by storage time. Although there were no initial differences in the firmness of samples among the treatments, firmness of the control sample was decreased faster than those of the aqueous $ClO_2$ treated samples for 8 days of storage. No significant changes in lightness, redness and yellowness of the samples by aqueous $ClO_2$ treatment were observed during storage. The sensory parameters including taste, flavor, color, texture and overall acceptance at the initial period were not different among treatments. However, all scores of the control were decreased faster than those of aqueous $ClO_2$ treated samples during storage.